California State University's chancellor told CNBC that plans for a mostly virtual fall semester were made due to fear of a second wave of coronavirus cases.

"This has been very hard to do, and I hope I'm wrong, to be honest," CSU's Timothy White said in an interview that aired Thursday on "Worldwide Exchange." "But we needed to be prepared to go in this direction."

"Most of the experts, epidemiologists and the science and the data that informs our decision-making indicates that there might be an even larger wave in the fall than the one we're just currently getting to be on the back side of," he added.

The California State University system — made up of 23 campuses, including San Diego State and Fresno State — announced earlier this week that most classes would be held online this fall. There are exceptions, with modifications, for research labs and clinical training for nurses, for example.

Colleges and universities across the U.S. are grappling with the same decision of how, or whether, in-person classes can be held safely in the fall term. But the timing of California State's announcement came to some as a surprise. Other universities have indicated their decisions will come later, perhaps in late June or early July.

White said it is important to offer clarity to students and their families so they can plan ahead. California State is the largest four-year public university system in the U.S., with around 480,000 students.

The early announcement was also important for staff and faculty so they can use the summer "to make sure the delivery of our curriculum in the fall is robust, engaging, vibrant" online like it is in person, he added.

The chancellor said he does not see any evidence that the system's decision would cause students to forgo enrollment. He also encouraged students to "lean in" to the virtual semester and be patient.

"By the time we get to August, it may very well be the case that we're able to open more than we think we will be now," White said. "We're preparing for virtual, with the hope of being able to pull back once we get into August and September a little bit."

Testing and contact tracing programs will be crucial components of plans to reopen campuses, higher education leaders have told CNBC. And many acknowledge that large lectures will likely not take place, even if it's safe to hold small group instruction.

Changes to the academic calendar are also under consideration. Bob Diamond, a trustee for Colby College in Maine, told CNBC on Wednesday that the school may delay the start of the semester to as late as January. Others, such as William Dudley, president of Washington and Lee University in Virginia, have floated the possibility of an earlier start, with no breaks to minimize travel to and from campus.